They begin at the Nass River, near the southern end of the Alaska Panhandle in the Canadian province of British Columbia and run to the Kelsall River, near the Chilkoot Pass, beyond which are the Alsek Ranges of the Saint Elias Mountains, and northwards into the Yukon Territory flanking the west side of the Yukon River drainage as far as Champagne Pass, north of which being the Yukon Ranges.

(Other peaks in the Stikine Icecap are higher than 2,600 m (8,530 ft), but they have relatively low topographic prominence.)

Physiographically, they are a section of the larger Pacific Border province, which in turn is part of the larger Pacific Mountain System physiographic division.

The granitic intrusions that form the Boundary Ranges are remnants of a Late Cretaceous volcanic arc system called the Coast Range Arc.

Rivers draining or transiting the Boundary Ranges include the: